Dota 2 is an action fantasy strategy video game being developed by Valve Corporation and the stand-alone sequel to the popular Warcraft III: Reign of Chaos and The Frozen Throne mod Defense of the Ancients. Formally announced on October 13, 2010 via the website of magazine Game Informer, the game is currently undergoing a closed beta phase and is scheduled for a full release in 2012. Dota 2 will be released through both retail and download by Valve's content delivery platform Steam, on which the game has been developed to run exclusively for both game launch and update delivery. Dota 2 will operate on Microsoft Windows and Mac OS X.

The game consists of session-based online multiplayer activity, with the primary objective of each match being for the teams to destroy their opposing team's fortified stronghold. Each player controls a player character called a "hero", who is given the responsibility of participating in team combat, which generally takes place along a series of lanes that connect their opposing bases, lined with defensive towers. The gameplay elements are largely incorporated from Defense of the Ancients, with the game's lead designer, "IceFrog", being the longest-serving and current developer of the Warcraft III mod.

Dota 2 combines the real-time strategy element of traditional top-down perspective, while also incorporating the leveling and itemization system of a role-playing video game. Players are pitted against each other as two distinct factions called the Radiant and the Dire. The Radiant is a faction based at the southwest corner of the map, while the Dire is a faction based at the northeast corner. Players assume the role of a "hero" - a strategically-powerful unit with special skills, who, through combat experience, may progress to a maximum level of twenty-five. The heroes' methods of combat are heavily influenced by their primary property, which can be physical strength, agility, or intelligence. The basic setup of Dota 2 places two strongholds containing critical structures called "Ancient Fortresses" at opposing ends of an evenly balanced map. These bases are connected by three main paths (referred to as "lanes") which are guarded by defensive towers and constantly spawning waves of units which march from one side to another, combating the towers as well as each other along the way. Players are split into two teams, each consisting of up to five players, to compete as the primary defenders for each Ancient Fortress.

The overall objective of each match is to battle through the opposing force's defenses, in order to arrive at and destroy the opponents' Ancient Fortress. Because Dota 2 is highly team-oriented, players must coordinate with their teams in order to achieve victory. The towers and stronghold defenses are invulnerable to attacks so long as the towers nearest to the enemy side still stand. Periodically, groups of weaker units commonly referred to as "creeps" are spawned, which move along their lane attacking any enemy unit or structure upon sight.

The currency of the game is gold, which is granted periodically, but typically accumulates at a more practical level by killing enemy units, which grants a distributed amount of gold to the killer's team, with the greater portion being retained by the killer themselves. A common technique utilized to prevent the opposing faction from accumulating gold from a kill is "denying", which constitutes killing an allied unit or destroying an allied structure and can be employed when the unit or structure it is about to be used on is close to death or collapse, respectively. Players also gain experience, which accumulates to gain higher levels. The greatest proportion of gold and experience comes from destroying higher priority forces, such as enemy heroes and towers.